Assumptions used for indirect estimates:
• The male and female mutation rates are equal (µ = v)
• In recessive conditions, there is no selection in favor of heterozygotes. This can be a serious source of error with some conditions.
• There is equilibrium between the rate at which mutation generates the disease genes and selection removes the disease genes.
• There is random mating, giving a Hardy-Weinberg distribution of genotypes.
X linked Recessive
mutation rate =
= 0.333 * (incidence of the condition) * (1 - (biological fitness of affected person)) =
= 0.333 * (coefficient of selection) * (gene frequency for recessive allele)
where:
• mutation rate is the rate per gene per generation
• coefficient of selection = 1 - (biological fitness of affected person)
Autosomal Dominant
mutation rate =
= 0.5 * (incidence of the condition) * (1 - (biological fitness of affected person)) =
= (coefficient of selection) * (gene frequency for the dominant allele)
Autosomal Recessive
mutation rate =
= (incidence of the condition) * (1 - (biological fitness of affected person)) =
= (coefficient of selection) * ((gene frequency for recessive allele) ^2)
